Internal combustion engine comprising a gas conveying system and operating method therefor

ABSTRACT

1. Internal combustion engine comprising a gas conveying system and operating method therefor.  
     2.1 The invention proposes an internal combustion engine ( 1 ) having a gas conveying system with a turbine ( 7 ) which can be driven by an airstream and a pump ( 8 ) which can be driven by the turbine ( 7 ) and by means of which gas can be fed to the exhaust system ( 3, 4, 5 ), as well as an operating method therefor.  
     2.2. According to the invention, when the internal combustion engine ( 1 ) is starting up, the quantity of fuel injected into it is set as a function of the delivery capacity of the pump ( 8 ). 2.3. Use in motor vehicles, in particular in passenger cars having an internal combustion engine with fuel injection.

The invention relates to an internal combustion engine comprising a gasconveying system and to an operating method therefor.

U.S. Pat. No. 6,094,909 has disclosed an internal combustion enginehaving a gas conveying system. The gas conveying system comprises aturbine which can be driven by an airstream and a pump which is drivenby the turbine and can deliver gas into the exhaust system. This gasconveying system is used when the internal combustion engine is startingup, in order to feed secondary air to the exhaust system so that unburntfuel constituents can be oxidized. The heat of combustion released isused to heat the exhaust-gas purification system, which is thereforeready to operate more quickly. The turbine is driven by an airstreamthat is caused by a pressure gradient present across a throttle elementin the intake line. However, secondary air is only supplied to asufficient extent when the turbine or the pump which it drives hasreached a sufficient rotational speed, which takes a certain amount oftime, and consequently the gas conveying system cannot provide secondaryair immediately after the internal combustion engine has been startedup. The gas conveying system has no further functions apart from thedelivery of secondary air when the internal combustion engine isstarting up.

By contrast, it is an object of the invention to provide an internalcombustion engine comprising a gas conveying system and an operatingmethod therefor which allow the internal combustion engine to operatewith low emissions and allow good utilization of the gas conveyingsystem.

According to the invention, this object is achieved by an internalcombustion engine has a throttle element (6), an intake line (2), inwhich the throttle element (6) is arranged, an exhaust system (3, 4, 5),and an air conveying system. The air conveying system includes a turbine(7) and a pump (8). The turbine (7) has a turbine inlet line (9) and aturbine outlet line (10), and is driven by an air stream flowing throughthe turbine outlet line (10). The pump (8) is driven by the turbine (7)and includes a pump inlet line (11) and a pump outlet line (12) viawhich air delivered by the pump (8) is fed to the exhaust system (3, 4,5). During engine start-up the air conveying system sets the quantity ofinjected fuel as a function of the delivery capacity of the pump (8).This object can also be achieved by a method that includes the steps of,during engine start-up, feeding air delivered by the pump (8) to theexhaust system (3, 4, 5) and setting the quantity of fuel injected as afunction of the delivery capacity of the pump (8).

The internal combustion engine according to the invention isdistinguished by the fact that when the internal combustion engine isbeing started up, the quantity of fuel injected into it can be set as afunction of the delivery capacity of the pump. It is preferable for fuelto be injected only once a minimum delivery capacity of the pump hasbeen reached, so that the start of fuel injection is dependent on thedelivery capacity of the pump. The result of this is that secondary aircan be added to the exhaust system at sufficient quantities with the aidof the pump when the fuel injection begins, in order to allowafter-oxidation of unburnt fuel residues. After-oxidation convertsincompletely burnt fuel by oxidation. The heat of the reaction which isreleased quickly heats the exhaust-gas purification system to itsoperating temperature, in particular downstream of the point at whichsecondary air is added. Consequently, effective exhaust-gas purificationcan be achieved quickly. In particular, the level of harmful hydrocarbonemissions (HC emissions) can be reduced during the starting phase. Bycontrast, if the beginning of fuel injection is not matched to thedelivery capacity of the pump and, for example, fuel is injected intothe combustion chambers of the internal combustion engine before thepump has reached a minimum delivery capacity, the atmospheric oxygenrequired as a reaction partner for after-oxidation of unburnt fuel inthe exhaust system is not present in sufficient quantities, andconsequently relatively large quantities of HC are emitted. On the otherhand, if too little fuel is injected in relation to the deliverycapacity of the pump, the air/fuel ratio (λ) in the exhaust systemrequired for after-oxidation is too high, and after-oxidation likewisecannot take place. This leads to late light-off of the exhaust-gascatalytic converters, with the result that pollutants are emitted for arelatively long period of time.

In one configuration of the invention, the turbine can be driven by apart-stream of the combustion air taken in by the internal combustionengine via the intake line, the part-stream being produced by a pressuregradient which is present across the throttle element. This measuremakes it possible to dispense with the need for additional units todrive the turbine of the gas conveying system.

In a further configuration of the invention, when the engine is startingup, the speed of the internal combustion engine can be set before thefuel injection commences, by actuation of the internal combustion engineor by actuation of an auxiliary unit assigned to the internal combustionengine. It is preferable for the speed of the internal combustion engineto be increased at the beginning of the engine start-up operation. Thismakes it possible to quickly empty the induction pipe region by theinternal combustion engine and to rapidly lower the induction pipepressure. Consequently, the mass of air sucked in per intake section israpidly reduced, so that an air/fuel ratio which is favorable foroperation of the internal combustion engine and for after-oxidation canbe set when the fuel injections begin. If the turbine of the gasconveying system is driven by the pressure drop which is present acrossthe throttle element in the induction pipe, moreover, the pump rapidlyreaches a sufficient delivery capacity as the result of the measureaccording to the invention. Consequently, sufficient quantities ofsecondary air can be delivered into the exhaust system even at a veryearly stage in the starting phase, with the result that in turneffective exhaust-gas purification can be provided quickly.

In a further configuration of the invention, the throttle element in theintake line can be set as a function of a pressure in the intake line.In particular if the turbine of the gas conveying system is driven bythe pressure drop that is present across the throttle element in theinduction pipe, it is possible for the throttle element to be set insuch a way according to the quantity of air taken in by the internalcombustion engine that the turbine of the gas conveying system quicklyreaches its rotational speed. Consequently, the pump likewise quicklyreaches a sufficient delivery capacity.

In a further configuration of the invention, the turbine can be drivenby an airstream which is generated by a gas conveying unit which isarranged in the turbine inlet line or in the turbine outlet line or isconnected to the turbine inlet line or to the turbine outlet line. Thismeasure allows the turbine to be run up to speed and therefore the pumpto reach a sufficient delivery capacity independently of thedifferential pressure which is present across the throttle element inthe intake line.

In a further configuration of the invention, the gas delivery unit isdesigned as an electrically driven gas conveying unit. The electricaldriving of the gas conveying unit allows accurate actuation of this unitand therefore of the gas conveying system as a whole.

In a further configuration of the invention, the gas conveying unit isdesigned as an evacuable gas vessel arranged in the turbine outlet line.If the evacuated gas vessel is opened, air is sucked into the vessel viathe turbine and the turbine is thereby driven. This requires virtuallyno auxiliary energy. Therefore, the measure according to the inventionallows the gas conveying system to operate independently of thedifferential pressure across the throttle element in a simple way.

In a further configuration of the invention, the gas stream delivered bythe pump can be set as a function of an air/fuel ratio in the exhaustsystem. The gas stream delivered is preferably set in such a way thatconditions which are advantageous for the after-oxidation areestablished downstream of the point at which the secondary air is added.It is preferable for the setting to be such that a λ value ofapproximately 1.2 is established.

In a further configuration of the invention, the gas stream delivered bythe pump can be fed to an exhaust manifold of the exhaust system and/ordirect to a catalytic converter of the exhaust system. This allowssecondary air to be made available to the exhaust-gas purificationsystem at the location where conditions are favorable forafter-oxidation to occur. When the internal combustion engine isstarting up, it is preferable for the secondary air to be fed to theexhaust manifold. If the internal combustion engine is being operatedunder rich conditions after it has been started up, secondary air may beadded on the entry side of a catalytic converter fitted in an underbodyposition in order to oxidize the unburnt exhaust-gas constituents.

In a further configuration of the invention, exhaust gas can be fed tothe pump via the pump inlet line, and the exhaust-gas stream deliveredby the pump can be fed to the intake line. As a result, the gasconveying system realizes exhaust-gas recirculation. Accordingly, inaddition to supplying secondary air, which occurs predominantly in thestarting phase, the gas conveying system also performs a furtherfunction and is therefore better utilized.

In a further configuration of the invention, a reduced-pressure vesselconnected via the pump inlet line can be evacuated by the pump. Thereduced pressure generated by the pump in the reduced-pressure vesselcan be used to drive servo units. The gas conveying system thereforeperforms a further function and is better utilized.

The method according to the invention is distinguished by the fact thatwhen the internal combustion engine is starting up, the quantity of fuelinjected is set as a function of the delivery capacity of the pump. Itis preferable for the injection of fuel to begin when the pump hasreached a minimum delivery capacity. This ensures that no unburnt fuelconstituents enter the exhaust system without atmospheric oxygen beingmade available at the same time to after-oxidize these unburnt fuelconstituents. Matching the quantity of fuel injected to the deliverycapacity of the pump ensures a λ value which is optimum forafter-oxidation in the exhaust manifold.

In one configuration of the method, when the engine is starting up andbefore the fuel injection begins, the throttle element is heldpredominantly closed and is only opened after the pump has reached aminimum delivery capacity. The result of this is that conditions whichallow effective after-oxidation of unburnt fuel constituents are veryquickly reached in the exhaust system.

In a further configuration of the method, the engine speed of theinternal combustion engine is increased as it is starting up before thefuel injection begins. Increasing the starting speed of the engineallows the air which is present in the induction pipe to be sucked outquickly, so that λ values which are favorable both for internalcombustion engine operation and in the exhaust system are very quicklyestablished. The starting engine speed can be increased by reducing thecompression work performed by the internal combustion engine. It ispreferable for the throttling of the internal combustion engine to berelieved, i.e. for the exhaust valves to remain open for a certainperiod of time or completely during the compression stroke. Furthermore,it is advantageous for auxiliary units which are driven by the internalcombustion engine to be switched off or decoupled.

In a further configuration of the method, the turbine, at least fromtime to time, is driven by an airstream which is delivered by a gasconveying unit which is arranged in the turbine inlet line or theturbine outlet line or is connected to the turbine inlet line or theturbine outlet line. This allows the turbine to be run up to speedquickly in the initial phase irrespective of the differential pressureacross the throttle element in the intake line and therefore allowssecondary air to be delivered by the pump very quickly. The gasconveying unit is preferably formed by an electrically operated pump orby a pressure vessel or reduced-pressure vessel.

In a further configuration of the method, the airstream delivered by thepump is set as a function of an air/fuel ratio in the exhaust system.The result of this is that conditions which are favorable for thedesired further reactions are established and further reactions cantherefore proceed in the desired way. It is preferable for a λ value of1.2 to be set in the exhaust manifold.

In a further configuration of the method, one of at least two additionpoints at which the airstream delivered by the pump is added to theexhaust gas is selected as a function of the operating state of theinternal combustion engine. On account of the fact that secondary aircan be fed to the exhaust system at at least two locations, it ispossible to react flexibly to the conditions in the exhaust system,which depend primarily on the operating state of the internal combustionengine.

In a further configuration of the method, the airstream delivered by thepump cools a definable part of the exhaust system if a predeterminablethreshold value for a temperature in the exhaust system is exceeded.With this configuration of the invention, the gas conveying systemadditionally performs a cooling function, with the result that it isbetter utilized, the exhaust system can be operated more reliably andthere is no need for other forms of cooling measures.

In a further configuration of the method, the pump at least from time totime removes exhaust gas from the exhaust system and feeds it to theintake line. In this case, the exhaust-gas stream fed to the intake lineis preferably set as a function of the operating state of the internalcombustion engine. Consequently, the gas conveying system performs anexhaust-gas recirculation function, so that the exhaust-gasrecirculation can be made independent of the pressure conditions in theexhaust system and in the intake system of the internal combustionengine. The exhaust-gas recirculation quantity can be set as required onaccount of being dependent on the operating state.

In a further configuration of the method, a reduced-pressure vesselassigned to the internal combustion engine is evacuated by the pump viathe pump inlet line in order to operate a servo system operated byreduced pressure. This further function of the gas conveying systemmakes it possible to draw additional benefit from this system and alsoconstitutes a simplification with regard to the components employed.

The text which follows provides a more detailed explanation of theinvention on the basis of drawings and associated examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic block diagram of an embodiment of the internalcombustion engine according to the invention with gas conveying system.

FIG. 2 shows a schematic block diagram of a further embodiment of theinternal combustion engine according to the invention with gas conveyingsystem.

FIG. 3 shows a schematic block diagram of a further embodiment of theinternal combustion engine according to the invention with gas conveyingsystem.

FIG. 4 shows a schematic block diagram of a further embodiment of theinternal combustion engine according to the invention with gas conveyingsystem.

FIG. 5 shows a schematic block diagram of a further embodiment of theinternal combustion engine according to the invention with gas conveyingsystem.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an internal combustion engine 1, which is, by way ofexample, a four-cylinder reciprocating-piston engine with sparkignition, referred to below just as engine for short, with a gasconveying system, intake system and exhaust system. When it isoperating, the engine 1 takes in air via the intake line 2 with athrottle element 6 arranged therein and discharges exhaust gas to theenvironment via the exhaust manifold 3 and the exhaust pipe 4 connectedto it. A catalytic converter 5 for purifying the exhaust gas is arrangedin the exhaust pipe 4. The catalytic converter is in this case designedas a starting catalytic converter arranged close to the engine. Theengine 1 is assigned a gas conveying system which comprises a turbine 7and a pump 8. The pump 8 can be driven via a drive shaft of the turbine7. A turbine inlet line 9 is connected to the turbine 7 on the inletside, and a turbine outlet line 10 is connected to the turbine 7 on theoutlet side. In each case the other end of the lines 9, 10 is connectedto the intake line 2, upstream or downstream, respectively, of thethrottle element 6, so that the turbine 7 is connected in parallel withthe throttle element. The airstream delivered by the turbine 7 can inthis case be controlled by a controllable valve 20 in the turbine outletline 10. A pump inlet line 11, which is in communication with theenvironment, is connected to the pump on the entry side. A pump outletline 12, which branches off to form the addition points 13, 14 in theexhaust manifold 3 and in the exhaust pipe 4, respectively, is connectedto the pump on the outlet side.

Furthermore, the engine 1 is assigned an injection system, not indicatedin more detail, for injecting fuel, either directly into the combustionchambers of the engine 1 or into the inlet region of the individualcylinders. Moreover, the engine 1 has an engine control unit (not shown)for controlling or regulating operation of the engine 1 and the systemsassigned to the engine 1. For this purpose, various sensors andmeasurement pick-ups (not shown), such as for example pressure sensors,an air mass flowmeter in the intake line 2 and exhaust-gas andtemperature sensors in the exhaust pipe 4, are arranged in the intakesystem and in the exhaust system. The signals from the sensors arerecorded and evaluated by the engine control unit. Moreover, the engine1 is assigned a starter (not shown), operation of which initiates thestarting operation and maintains the starter until the engine isoperating independently.

The mode of operation of the installation illustrated in FIG. 1 isexplained below.

In a first field of use, the gas conveying system is used to achievelow-emission starting or warming-up of the engine 1. For this purpose,it is crucial that the catalytic converter 5 arranged in the exhaustpipe 4 be able to operate with sufficient efficiency, i.e. at what isknown as its light-off temperature, sufficiently quickly. For thispurpose, after a certain instant in the starting operation, the engineis operated with a rich air/fuel ratio, and the reducing constituents inthe rich exhaust gas obtained are burnt by after-oxidation upstream ofthe catalytic converter 5. In the text which follows, the air/fuel ratioof the mix fed to the engine 1 is referred to as engine λ or λ_(E). Theheat of combustion which is released during the after-oxidation heatsthe catalytic converter 5, so that the catalytic converter 5 can quicklyperform its purification function. As a result of secondary air beingsupplied, the exhaust gas reaches the oxygen content required for theafter-oxidation to proceed. The supply of secondary air is effected bythe pump 8 driven by the turbine 7. Actuation of a switching unit (notshown) in the pump outlet line 12 opens up the addition point 13 in theexhaust manifold 3 for the addition of secondary air and blocks theaddition point 14. The pressure drop which is present across thethrottle element 6 and is caused by the flow of the air taken in by theengine 1 is used to drive the turbine. This pressure drop acts acrossthe turbine inlet line 9 and the turbine outlet line 10 and thereforecauses air to flow across the turbine 7, thereby driving the turbine 7and the pump 8 coupled to it.

A precondition for the after-oxidation to take place is that acombustible mixture be present. Therefore, for low-emission starting ofthe engine, it is important to match the fuel injection quantity andsecondary air delivery. The aim is for the after-oxidation to commenceas early as possible when starting up the engine 1.

According to the invention, during the starting operation the quantityof fuel injected is set as a function of the delivery capacity of thepump 8. It is preferable for no fuel to be injected initially when thestarting operation begins, since at this instant the pump 8 is not yetdelivering any secondary air. The reason for this is that the pressuredrop across the throttle element 6 is not initially present or is toolow. Since the speed of the engine 1, at typically approximately 200rpm, is relatively low during the starting operation, a pressure dropacross the throttle element is built up relatively slowly. To acceleratethe build-up of pressure, the throttle element is set as a function ofthe reduced pressure which is present in the intake line 2 downstream ofthe throttle element 6. It is preferable for the throttle element to becompletely closed in the absence of reduced pressure during the startingoperation. This is the case right at the beginning of the startingoperation. The result of this is that the air in the line volume betweenthrottle element 6 and air inlet of the engine cylinders is rapidlysucked out by the engine. Consequently, a differential pressure acrossthe throttle element 6 is quickly built up, and accordingly the turbine7 quickly reaches its rotational speed and the pump 8 delivers secondaryair correspondingly quickly.

The injection of fuel preferably only begins when the pump 8 has reacheda minimum delivery capacity, which can be determined, for example, withthe aid of a rotational speed sensor at the pump 8. The period of timefrom the beginning of starter actuation to the beginning of fuelinjection can advantageously also be set in a time-controlled fashion.In this case, it is possible, for example, to make use of a table storedin the engine control unit, in which the periods until the fuelinjection begins are stored. In this case, it is additionally possibleto take account of the coolant temperature of the engine 1 or theambient temperature.

The quantity of fuel injected per unit time is preferably set in such away that an engine λ of approximately λ_(E)=0.8 results. Therefore, anignitable mixture is present in the combustion chambers of the engine 1,and the engine 1 can continue to operate without starter assistance.When this independent engine running begins, the engine speed, theintake air quantity and the pressure drop across the throttle element 6rise. In accordance with the setting as a function of reduced pressure,the throttle element 6 is opened when a predeterminable reduced-pressurevalue is reached. The quantity of secondary air delivered into theexhaust manifold 3 by the pump 8 is limited with the aid of the settingvalve 20 in the turbine exhaust line 10 in such a way that conditionswhich are favorable for after-oxidation result in the exhaust manifold3. The secondary air quantity is preferably set in such a way that anair/fuel ratio, also referred to below as exhaust-gas λ or λ_(EG), ofapproximately λ_(EG)=1.2 is set for the exhaust gas.

The time required to deliver a sufficient quantity of secondary air canbe shortened still further if the starting speed of the engine 1 isincreased during the starter operation. According to the invention, thisis achieved by reducing the compression work performed by the engine 1.With a variable compression ratio, this is reduced in the starter phaseof the starting operation. Furthermore, it is advantageous to relievethe throttling of the engine 1 by opening the outlet valves in thecompression stroke. It is also advantageous to temporarily decoupleauxiliary units which are driven by the engine 1. By way of example, itis possible to decouple a generator or a coolant pump. This reduces themechanical power loss from the engine 1 and increases the engine speedduring starter operation.

After stable and independent engine running and the light-offtemperature of the starting catalyst 5 have been reached, the startingoperation can be considered to have ended and the addition of secondaryair to the exhaust manifold 3 is concluded. The ending of the additionof secondary air can be effected by closing the setting valve 20 orclosing a switching device (not shown) in the pump outlet line 12.

In a further field of use, the gas conveying system is employed toreduce emissions during rich operation of the engine 1 outside thestarting operation, for example during acceleration or under full load.Under these conditions, a pressure drop which is sufficient to operatethe turbine 7 is present across the throttle element. In thisapplication of the gas conveying system, the pump 8 passes secondary airinto the exhaust gas at the addition point 14 on the entry side of acatalytic converter 5 which is in this case preferably arranged remotefrom the engine. In the process, an exhaust-gas λ of approximatelyλ_(EG)=1.0 is set. Under these conditions, reducing exhaust-gasconstituents are oxidized by the catalytic converter 5 and the level ofpollutants is reduced even during acceleration or full-load operation.

In a further application area, the gas conveying system is used to coolpart of the exhaust system. By way of example, the pump 8 can be used toblow relatively cool ambient air into the air gap of a catalyticconverter housing or exhaust manifold with air gap insulation. Thisfunction of the gas conveying system is preferably activated when adetermining temperature in the exhaust system is exceeded. This preventsthe exhaust system from being overheated or damaged and maintains thefunction of components which have a purifying action.

FIG. 2 diagrammatically depicts the arrangement of the engine 1 and thegas conveying system in a further preferred embodiment. The designationof functionally equivalent components corresponds to that employed inFIG. 1. In addition to the embodiment illustrated in FIG. 1, the gasconveying system is in this case assigned a further gas conveying unit,which is designed as an electrically driven air pump 15 which isconnected to a branch of the turbine inlet line 9. Moreover, a shut-offvalve 21, which can be used to shut off the connection to the intakeline 2 upstream of the throttle element 6, is provided in the turbineinlet line 9. The turbine 7 can be run up to speed more quickly with theaid of the air pump 15 when the engine 1 is starting up. For thispurpose, at the beginning of starter operation, the shut-off valve 21 isclosed, the valve 20 is opened and the air pump is switched on.Therefore, air is delivered via the turbine 7 virtually as soon as thestarting operation begins. Consequently, a quantity of secondary airwhich is sufficient for after-oxidation can be fed to the exhaustmanifold 3 after just a short time irrespective of the build-up ofdifferential pressure across the throttle element 6, and the fuelinjection is performed in the same way as in the embodiment shown inFIG. 1. When a sufficient differential pressure has been built up acrossthe throttle element 6, the air pump is switched off and the shut-offvalve 21 is opened. The turbine 7 is then driven by the airstreamflowing through the lines 9, 10, which is caused by the differentialpressure across the throttle element 6. All the further functions of thegas conveying system are present in the same way as in the embodimentshown in FIG. 1.

FIG. 3 diagrammatically depicts the arrangement of the engine 1 and thegas conveying system in a further preferred embodiment. Functionallyequivalent components are designated by the same references as inFIG. 1. In addition to the embodiment illustrated in FIG. 1, the gasconveying system is in this case assigned a further gas conveying unit,which is designed as an evacuable gas vessel 16 which is arranged in asecondary branch of the turbine outlet line 10. The gas vessel can beshut off on the inlet side and the outlet side by a shut-off valve 22and 23, respectively. The turbine 7 can be run up to speed more quicklywith the aid of the evacuated gas vessel 16 during starting of theengine 1. For this purpose, when the starter operation begins, theshut-off valve 22 is opened on the inlet side of the evacuated gasvessel 16. The valves 20 and 23 remain closed. Therefore, air isconveyed into the evacuated gas vessel 16 via the turbine 7 virtually assoon as the starting operation begins. Consequently, a quantity ofsecondary air which is sufficient for after-oxidation can be fed to theexhaust manifold 3 after a short time irrespective of the build-up ofdifferential pressure across the throttle element 6, and the fuelinjection is performed in the same way as in the embodiment shown inFIG. 1. When a sufficient differential pressure has been built up acrossthe throttle element 6, the valve 20 is opened and the valve 22 isclosed. The turbine 7 is then driven by the airstream through theturbine inlet line 9 and the branch of the turbine outlet line 10provided with the valve 20. The airstream is in this case produced bythe differential pressure across the throttle element 6. To enable theturbine to be run up to speed quickly independently of the build-up ofdifferential pressure across the throttle element 6, the gas vessel 16must of course be of sufficient size. All the further functions of thegas delivery system are similar to the embodiment shown in FIG. 1. Forrenewed evacuation of the gas vessel 16, during normal engine operationthe valve 23 is open and the valve 22 is closed. In particular at anengine operating point with a high subatmospheric pressure downstream ofthe throttle element 6, such as for example during overrun operation ata high engine speed, the gas vessel 16 can be evacuated sufficiently fora further starting operation.

FIG. 4 diagrammatically depicts the arrangement of the engine 1 and thegas conveying system in a further preferred embodiment. Functionallyequivalent components are designated by the same references as thoseused in FIG. 1. With the embodiment illustrated in FIG. 4, it ispossible to provide exhaust-gas recirculation in addition to thefunctions of the embodiment illustrated in FIG. 1. For this purpose, thegas delivery system has a branch, provided with a valve 24, of the pumpinlet line 11, which branch is in communication with the exhaust pipe 4.That part of the pump inlet line 11 which is in communication with theenvironment can likewise be shut off by the valve 25 arranged therein.Furthermore, a branch of the pump outlet line 12 which leads into theintake line 2 downstream of the throttle element 6 is provided. Thisbranch can likewise be shut off by the settable valve 26. if the gasdelivery system is not required to deliver secondary air, during normalengine operation the pump 8 can deliver exhaust gas into the intake line2 at the addition point 18. For this purpose, the valve 24 is opened andthe valve 25 is closed. The valve 26 is opened according to theexhaust-gas recirculation rate that is to be provided. The pump 8 isdriven as described above by the airstream across the turbine 7 causedby the differential pressure across the throttle element 6. Theembodiment shown in FIG. 4 can provide a higher exhaust-gasrecirculation rate compared to standard exhaust-gas recirculationsystems with passive exhaust-gas recirculation, in which therecirculated quantity of exhaust gas is determined by the differentialpressure that is present between exhaust pipe and intake pipe. Thereason for this is the active exhaust-gas delivery provided by the pump8. All the further functions of the gas delivery system are present inthe same way as in the embodiment shown in FIG. 1.

FIG. 5 diagrammatically depicts the arrangement of the engine 1 and thegas conveying system in a further preferred embodiment. Functionallyequivalent components are designated by the same designations as inFIG. 1. Unlike in the embodiment illustrated in FIG. 1, the pump inletline 11 is in this case connected to an evacuable gas vessel 17. Aconnection to the environment which can be shut off by a valve 27 isstill present. If the gas conveying system is not required to deliversecondary air, the gas vessel can be evacuated by the pump 8 duringnormal engine operation. For this purpose, the valve 27 is closed. Theair which is extracted from the gas vessel 17 can be fed to the exhaustgas via the pump outlet line 12 or can be released to the environmentvia a branch which is not shown. Servo systems which are operated byreduced pressure, are connected to the gas vessel 17 and are notindicated in more detail here can be operated by the reduced pressuregenerated in the gas vessel 17. All the further functions of the gasconveying system are still present in the same way as in the embodimentshown in FIG. 1.

With the embodiments of internal combustion engine and gas conveyingsystem in accordance with the invention, it is possible, as illustrated,to provide low-emission operation of the internal combustion engine. Thefunctions of the gas conveying system which are present in addition tothe delivery of secondary air means that the gas conveying system isutilized better and that some components can be eliminated. In thiscontext, it will be understood that modifications to the embodimentsillustrated are possible within the scope of the invention by the use ofadditional lines or valves in the gas converying system.

1. An internal combustion engine with fuel injection, having an intakeline (2), in which a throttle element (6) is arranged, an exhaust system(3, 4, 5) and a gas conveying system having a turbine (7), which can bedriven by an air stream and to which a turbine inlet line (9) and aturbine outlet line (10) are connected, and a pump (8), which can bedriven by the turbine (7) and has a pump inlet line (11) and a pumpoutlet line (12), via which gas delivered by the pump (8) can be fed tothe exhaust system (3, 4, 5), characterized in that when the internalcombustion engine (1) is starting up, the quantity of fuel injected intoit can be set as a function of the delivery capacity of the pump (8). 2.The internal combustion engine as claimed in claim 1, characterized inthat the turbine (7) can be driven by a part-stream of the combustionair taken in by the internal combustion engine (1) via the intake line(2), the part-stream being produced by a pressure gradient which ispresent across the throttle element (6).
 3. The internal combustionengine as claimed in claim 1, characterized in that when the engine isstarting up, the speed of the internal combustion engine (1) can be setbefore the fuel injection commences, by actuation of the internalcombustion engine (1) or by actuation of an auxiliary unit assigned tothe internal combustion engine (1).
 4. The internal combustion engine asclaimed in claim 1, characterized in that when the engine is startingup, the throttle element (6) can be set as a function of a pressure inthe intake line (2).
 5. The internal combustion engine as claimed inclaim 1, characterized in that the turbine (7) can be driven by anairstream which is generated by a gas conveying unit (15; 16) which isarranged in the turbine inlet line (9) or in the turbine outlet line(10) or is connected to the turbine inlet line (9) or to the turbineoutlet line (10).
 6. The internal combustion engine as claimed in claim5, characterized in that the gas conveying unit is designed as anelectrically driven gas conveying unit (15).
 7. The internal combustionengine as claimed in claim 5, characterized in that the gas conveyingunit is designed as an evacuable gas vessel (16) arranged in the turbineoutlet line (10).
 8. The internal combustion engine as claimed in claim1, characterized in that the gas stream delivered by the pump (8) can beset as a function of an air/fuel ratio in the exhaust system (3, 4, 5).9. The internal combustion engine as claimed in claim 1, characterizedin that the gas stream delivered by the pump (8) can be fed to anexhaust manifold (3) assigned to the exhaust system (3, 4, 5) and/ordirect to a catalytic converter (5) assigned to the exhaust system (3,4, 5).
 10. The internal combustion engine as claimed in claim 1,characterized in that exhaust gas can be fed to the pump (8) via thepump inlet line (11), and the exhaust-gas stream delivered by the pump(8) can be fed to the intake line (2).
 11. The internal combustionengine as claimed in claim 1, characterized in that a reduced-pressurevessel (17) connected via the pump inlet line (11) can be evacuated bythe pump (8).
 12. A method for operating an internal combustion enginewith fuel injection and having an intake line (2), in which a throttleelement (6) is arranged, an exhaust system (3, 4, 5) and a gas conveyingsystem, which comprises a turbine (7) that can be driven by an airstreamand a pump (8) that can be driven by the turbine (7), in which method,at least when the engine is starting up, gas delivered by the pump (8)is fed to the exhaust system (3, 4, 5), characterized in that when theinternal combustion engine (1) is starting up, the quantity of fuelinjected is set as a function of the delivery capacity of the pump (8).13. The method as claimed in claim 12, characterized in that when theengine is starting up, before the fuel injection begins the throttleelement (6) is held predominantly closed and is only opened after thepump has reached a minimum delivery capacity.
 14. The method as claimedin claim 12, characterized in that the engine speed of the internalcombustion engine (1) is increased as it is starting up before the fuelinjection begins.
 15. The method as claimed in claim 12, characterizedin that the turbine (7), at least from time to time, is driven by anairstream which is delivered by a gas conveying unit (15; 16) which isarranged in the turbine inlet line (9) or the turbine outlet line (10)or is connected to the turbine inlet line (9) or the turbine outlet line(10).
 16. The method as claimed in claim 12, characterized in that theairstream delivered by the pump (8) is set as a function of an air/fuelratio in the exhaust system (3, 4, 5).
 17. The method as claimed inclaim 12, characterized in that one of at least two addition points (13,14) in the exhaust system (3, 4, 5) at which the airstream delivered bythe pump (8) is added to the exhaust gas is selected as a function ofthe operating state of the internal combustion engine (1).
 18. Themethod as claimed in claim 12, characterized in that the airstreamdelivered by the pump (8) cools a definable part of the exhaust system(3, 4, 5) if a predeterminable threshold value for a temperature in theexhaust system (3, 4, 5) is exceeded.
 19. The method as claimed in claim12, characterized in that the pump (8) at least from time to timeremoves exhaust gas from the exhaust system (3, 4, 5) and feeds it tothe intake line (2).
 20. The method as claimed in claim 12,characterized in that a reduced-pressure vessel (17) assigned to theinternal combustion engine (1) is evacuated by the pump (8) via the pumpinlet line (11) in order to operate a servo system operated by reducedpressure.